The poll, which was conducted from last Monday to Sunday, was the first national four-way poll to at least partially be conducted after Trump, the Republican nominee, renewed the so-called birther controversy about President Barack Obama's birthplace.

Trump last week publicly said for the first time unequivocally that Obama was born in the US. His announcement created a backlash, however, after he declined to apologize to Obama after spending years as the public face of those trying to undermine the president's legitimacy. Trump also in his announcement falsely blamed the Clinton campaign for starting the birther movement.

Tuesday's poll was also the first to include results from the time after Clinton returned to the campaign trail following her health episode on September 11.

Clinton did not hold a lead of greater than 3 points over Trump in the previous eight polls to also include Libertarian nominee Gary Johnson and Green Party nominee Jill Stein, and her lead over the Republican nominee had dipped beneath 1 point in the RealClearPolitics polling average.